Zero till and full stubble retention
Under zero-tillage and stubble retention, water infiltration into water repellent sands is improved compared with annual cultivation (~10cm depth with a wide tine) and stubble removal.
Research outcomes from the project Novel solutions for managing non-wetting soils revealed that even though zero-till and stubble retention made the soil more water repellent, due to higher levels of soil carbon, the system improved water infiltration into the ground.
As a result soil water contents were higher and this improved crop performance. The results suggest that bio-pores, formed by the roots and small animals, are preserved creating channels for water movement (Figure 1). In a cultivated soil these bio-pores are broken up restricting water entry (Figure 2).
Root channels persist under zero-till even after the crops have matured and conduct water into the soil well after the establishment of the new season’s crop (Figure 3). Where the soil is cultivated water entry is dependent on the development of new root channels by the emerging crop, but the surface soil between the new rows remains dry (Figure 4).
Figure 1: Zero-till prior to seeding. Infiltration of water
(blue areas) occurs down the old crop row.
Figure 2: Cultivated soils prior to sowing. Pathways for water movement are disrupted and blue dye remains on the surface where it dries into a crust.
Figure 3: Zero-till in July 2011, two months after seeding. Infiltration of water is still evident in the inter-row down the old 2010 crop row.
New pathways for water entry have also developed below the new crop.
Figure 4: Cultivated soil in July 2011. New pathways for
water movement only occur below the developing wheat
crop. The cultivated inter-row remains dry.